JPH0490220A - Selective antenna diversity receiver - Google Patents

Abstract

PURPOSE:To effectively operate the receiver even in a time division radio communication system using a linear modulation wave by integrating a reception input electric field level hourly by each antenna just before an assigned time slot and selecting an antenna with the best reception state based on the result of comparison. CONSTITUTION:A switching control circuit 18 selects an antenna 11 just before a time slot A, an RSSI signal by the antenna 11 is integrated for a prescribed time and a sample-hold circuit 16 samples and holds the signal. Then the switching control circuit 18 selects an antenna 12 and the RSSI signal by the antenna 12 is integrated by a prescribed time only. The time integration value of the RSSI signal by the antenna 12 and the time integration value of the RSSI signal by the antenna 11 sampled and held by the sample-hold circuit 16 are inputted to a comparator 17, and the result of comparison is outputted to the switching control circuit 18 and an antenna with excellent reception state is selected based on the result of comparison.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention is directed to time division multiplexing (hereinafter referred to as
The present invention relates to an antenna selection diversity receiving device used in a TDM wireless communication system.

[Conventional technology]

FIG. 10 is a block diagram showing a control circuit of a conventional antenna selection diversity receiving apparatus disclosed in, for example, European Patent No. 0318665. In the figure,
1 is the received electric field (hereinafter referred to as RSS) from a wireless receiver (not shown) as the received input electric field level by each antenna.
This is a sample and hold circuit that samples and holds a signal (referred to as I).

2 is the R55I signal sampled and held in this sample and hold circuit 1 and the RSS from the radio receiver.
This is a comparison circuit that compares the levels of I signals. 3 is the first ~
It is composed of third exclusive OR gates 4 to 6 and a D flip-flop 7, and controls an antenna switch circuit (not shown) based on the comparison result from the comparison circuit 2 to select the antenna with the best reception condition. This is the antenna switch control circuit to select.

Next, the operation will be explained.

In land-based mobile radio communications, there is usually no line-of-sight between radio stations, and radio waves arrive after being scattered, diffracted, and reflected, so the propagation path becomes a multiwave propagation path. This multi-wave interference generates a random standing wave electromagnetic field distribution, and as the mobile station travels within this electromagnetic field distribution, fading occurs, causing reception by one of the mobile station's antennas. The input electric field level varies as shown in FIG.

Therefore, in such mobile radio communications, an antenna selection diversity method is generally adopted in which a plurality of antennas are prepared and the antenna with the best reception condition at that time is selected. Here, the fading frequency of this fading is approximately 100 Hz in a frequency band of 900 MHz, assuming that the traveling speed of the mobile station is 1100 K/h.

The antenna selection diversity in FIG. 10 will be explained in detail below. Here, FIG. 12 is a time chart for explaining the operation. As shown in FIG. 12, it is assumed that this mobile radio communication system has two time slots "A" and "B", of which time slot A is assigned to the radio receiver.

First, during the period of time slot B immediately before the assigned time slot A, the received input electric field levels received by the two antennas are monitored. The RSS I signal from one antenna, which is first detected by the radio receiver, is input to the sample and hold circuit 1 where it is sampled and held, and is also input to the inverting input terminal of the comparison circuit 2.

On the other hand, the output signal of the sample and hold circuit 1 is input to the non-inverting input terminal of the comparison circuit 2. Therefore, when the RSS I signal from the other antenna is input from the radio receiver, the comparator circuit 2 compares the R85I signal with the sampled and held R35l signal, and sends the comparison result to the antenna switch control circuit 3. send.

In the antenna switch control circuit 3, the comparison result is inputted to one input terminal of the first exclusive OR gate 4.

The other input terminal of this exclusive OR gate 4 receives the Q output of a D flip-flop 7 whose data port receives the output of the exclusive OR gate 4. Further, a sample and hold signal is input to one input terminal of the second exclusive OR gate 5, and the other input terminal is fixed at a high level (+5V).

Therefore, this sample and hold signal is inverted by the second exclusive OR gate 5.

This sample hold signal is applied to the D flip-flop 7.
The Q output of the D flip-flop 7 is also input to one input terminal of the third exclusive OR gate 6.

Further, the output of the second exclusive OR gate 5 is given to the other input terminal of this exclusive OR gate 6, and the exclusive OR thereof is outputted from the antenna switch control circuit 3 as an antenna switch output. be done.

Therefore, based on the comparison result of the RSS I signals from each antenna immediately before time slot A and the antenna switch output at that time, a new antenna switch output signal is output and the antenna with the higher R3S I signal level is selected. Ru.

FIG. 13 is an explanatory diagram showing the transition of a carrier wave on a vector plane in minimum phase shift keying (hereinafter referred to as MSK). As shown in the figure, in MSK, only the phase of the carrier wave vector changes and its magnitude remains constant. Therefore, the instantaneous R35 immediately before the assigned time slot
By comparing the I signals, it is possible to select an antenna with a good reception condition within the allocated time slot with a high probability.

Such an antenna selection diversity method is generally effective for use with modulation methods having a constant envelope, such as phase modulation and frequency modulation.

[Problems to be Solved by the Invention] Since the conventional antenna selection diversity receiving device is configured as described above, it is effective in a time division wireless communication system using a modulation method with a constant envelope. Linear modulation that changes not only the phase but also its envelope component, such as phase phase shift keying (hereinafter referred to as BPSK), quadrature phase shift keying (hereinafter referred to as QPSK), or 16-value quadrature amplitude modulation (hereinafter referred to as 16QAM) The problem was that it could not be applied to time-division wireless communication systems using modulated waves.

The inventions described in claims (1) and (2) have been made to solve the above-mentioned problems, and provide an antenna selection diversity receiving device that is effective even in a time division wireless communication system using linear modulated waves. The purpose is to obtain.

[Means to solve the problem]

The antenna selection diversity receiving device according to the invention described in claim (1) calculates the reception input electric field level at each antenna detected immediately before the allocated time slot,
An integration circuit that integrates over a certain period of time, a comparison circuit that compares the time integral value for each antenna, and a switching control circuit that selects the antenna with the best reception condition based on the comparison results and controls the antenna switch circuit. It has been established.

Furthermore, the antenna selection diversity receiving device according to the invention described in claim (2) is configured to detect the received input electric field level at each antenna, which is detected alternately a plurality of times, for a certain period of time before the assigned time slot. An integrator circuit that performs integration, a prediction circuit that predicts changes in the received input electric field level at each antenna within an assigned time slot based on the time-integrated value at each antenna, and a prediction circuit that predicts changes in the received input electric field level at each antenna within an assigned time slot based on the time-integrated value at each antenna. A switching control circuit is provided to select the best antenna and control the antenna switch circuit.

[Operation] The integrating circuit in the invention according to claim (1) time-integrates the received input electric field level at each antenna immediately before the assigned time slot, averages changes in the envelope of modulated data, and performs switching. Based on the comparison results of the integral values, the control circuit controls the antenna switch circuit to select the antenna with the best reception condition, thereby creating an antenna selection diversity receiving device that is effective even in systems using linear modulated waves. The prediction circuit in the invention according to claim (2) is characterized in that the prediction circuit calculates the assigned time slot based on the time integral value of the received input electric field level at each antenna, which is detected alternately multiple times before the assigned time slot. By predicting the change in the received input electric field level at each antenna within the time slot, and controlling the antenna switch circuit based on the prediction result, the switching control circuit selects the antenna with the best reception condition. An antenna selection diversity receiving device that is effective even in a system using linear modulated waves is realized.

〔Example] Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing an antenna selection diversity receiving apparatus according to an embodiment of the invention as set forth in claim (1). In the figure, 11 and 12 are antennas prepared independently of each other.

13 is an antenna switch circuit for switching these antennas 11 and 12, and 14 is a TDM receiver as a radio receiver of the wireless communication system. 15 is the TDM receiver 1 detected by this TDM receiver 14
This is an integration circuit that integrates the R5S I signal at each antenna 11.12 immediately before the time slot assigned to time slot 4 for a certain period of time.

16 is a sample and hold circuit that samples and holds the time integral value from this integrating circuit 15; 17 is a sample and hold circuit that samples and holds the previous time integral value sampled and held in this sample and hold circuit 16 and the current time integral value from the integrating circuit 15; This is a comparison circuit that compares the 18 is this comparison circuit]
7, selects the antenna with the best reception condition, controls the antenna switch circuit 13, and also controls the integration circuit 15 and sample hold circuit 16.
and a switching control circuit that provides a timing signal to the comparison circuit 17.

Next, the operation will be explained.

First, changes in the envelope of linear modulation will be explained. FIG. 2 is an explanatory diagram showing transitions on the amplitude/phase plane of a carrier wave in a modulation method called 71:/4 shift QPSK. As shown in FIG. 2, the amplitude and phase of the carrier wave vary depending on the data to be transmitted. Also, the third
The figure is an explanatory diagram showing only changes in the envelope level. Since the envelope level changes greatly as shown in the figure, it is meaningless to sample and hold only the instantaneous R85I signal and compare it.

Here, a data transmission rate of several tens of Kbps to several hundreds of Kbps is generally used, which is a sufficiently large value compared to the fading frequency of about 100 Hz mentioned above.

Further, FIG. 4 is an explanatory diagram showing an example of the reception time slot and the input levels of the antennas 11 and 12 on the time axis. As shown in the figure, the input level of each antenna 11, 12 includes fluctuations due to frequency fading up to about 100 Hz at most and changes due to modulation data.

Therefore, the antenna IJ (12
), it is necessary to detect only the fluctuations in the antenna input level due to fading after the level changes due to modulation are removed. Therefore, R3 by each antenna 11.12 immediately before the allocated time slot
The level of the SI signal is integrated over a certain period of time, and the comparison is made after averaging unknown level fluctuations due to modulation data.

The operation of the embodiment shown in FIG. 1 will be described in detail below. Here, FIG. 5 is a time chart for explaining the operation. FIG. 5(a) shows the control signal from the switching control circuit 18 to the antenna switch circuit 13, and FIG. timing signal to, (C
) are the same (timing signal to the sample and hold circuit 16, (d) is the same (timing signal to the comparison circuit 17,
(e) shows the comparison result from the comparison circuit 17 to the switching control circuit 18. Also in this case, it is assumed that time slot A is allocated as in the conventional case.

First, immediately before time slot A, switching control circuit 1
8 sends out a control signal for causing the antenna switch circuit 13 to select the antenna 11. Antenna switch circuit 13
connects the antenna 11 to the TDM receiver 14 in response to this control signal, and the TDM receiver 14 monitors the R3S I signal from the antenna 1 and sends it to the integrating circuit 15.

Thereafter, the switching control circuit 18 sends a timing signal to the integrating circuit 15 to integrate the R3S I signal from the antenna 11 for a certain period of time. Next, the switching control circuit 18 gives a timing signal to the sample and hold circuit 16 to sample and hold the time integral value of the R3S I signal from the antenna 11 integrated by the integration circuit 15.

Next, the switching control circuit 18 provides the antenna switch circuit 13 with a control signal that causes the antenna 12 to be selected. In response to this control signal, the antenna switch circuit 13 connects the antenna 12 to the TDM receiver 14 and sends the R5S I signal from the antenna 12 to the integration circuit 15. Thereafter, the switching control circuit 18 sends the timing signal again to the integrating circuit 15 to integrate the R3S I signal from the antenna 12 for a certain period of time.

The time integral value of the R8S I signal by this antenna 12 and the time integral value of the RSS I signal by the antenna 11 sampled and held by the sample and hold circuit 16 are as follows.
The signals are respectively input to the comparison circuit 17. When the comparison circuit 17 receives a timing signal instructing the start of comparison from the switching control circuit 18, it compares the predistribution time integral values and outputs the comparison result to the switching control circuit 18. Based on this comparison result, the switching control circuit 18 selects an antenna with better reception condition (antenna 12 in the illustrated example), and sends a control signal to the antenna switch circuit 13 to connect the Sowa to the TDM receiver 14. do.

In addition, in the above embodiment, the RSS I signal from each antenna is monitored only immediately before the allocated time slot, but the RSS I signal from the selected antenna is further monitored within the period of the allocated time slot.
Integration of the I signal may be repeated, and when the integrated value falls below a certain value, the antenna may be switched to the other antenna.

FIG. 6 is a block diagram showing such an embodiment, and FIG. 7 is a time chart for explaining its operation.
Components that are the same as or corresponding to those in the embodiment shown in the figures are given the same reference numerals to avoid redundant explanation. In Figure 6, 19
is a comparison circuit that compares the time integral value from the integration circuit 15 with a predetermined reference value in accordance with a timing signal from the switching control circuit 18, and outputs the comparison result to the switching control circuit 18.

As shown in FIG. 7(b), the switching control circuit 18 sends out a timing signal instructing the integration circuit 15 to integrate for a certain period of time even in the assigned time slot A, and the switching control circuit 18 sends out a timing signal instructing the integration circuit 15 to perform integration for a certain period of time even in the assigned time slot A, so that the selected antenna R according to 11(12)
The time integral value of the SSI signal is input to comparison circuits 17 and 19. The switching control circuit 18
During the period, the timing signal shown in FIG. 7(f) is sent only to the comparator circuit 19, and the comparator circuit 19 responds to the timing signal and compares the time integral value taken by the receiver with a reference value.

The comparison circuit 19 sends the result to the switching control circuit 18 as the comparison result shown in FIG. 7(g), and the switching control circuit 18 selects the currently selected antenna 1 based on the comparison result.
2(11), the control signal shown in FIG. 7(a) is sent to the antenna switch circuit 13 and the other antenna 11(1
2).

FIG. 8 is a block diagram showing an antenna selection diversity receiving apparatus according to an embodiment of the invention as set forth in claim (2).
The same or equivalent parts as in the embodiment of the invention described in 1) are given the same reference numerals. In the figure, reference numeral 20 indicates each antenna 11°1 which is detected alternately multiple times before the assigned time slot and is time-integrated by the integrating circuit 15.
This is a prediction circuit that predicts changes in the receiving input electric field level at each antenna 11 and 12 based on each time integral value of the RSS I signal according to No. 2, and outputs the prediction result to the switching control circuit 18.

Next, the operation will be explained. Here, FIG. 9 is a time chart for explaining the operation.

A control signal shown in FIG. 9(a) is sent from the switching control circuit 18 to the antenna switch circuit 13, and within time slot B, the RSS I signal from each antenna is monitored multiple times while switching between each antenna 11 and 12 alternately. and sequentially sends it to the integrating circuit 15. In the integrating circuit 15, FIG.
In accordance with the timing signal from the switching control circuit 18 shown in b), the received RSS I signal is integrated over a certain period of time, and the time integral value is outputted to the prediction circuit 20.

As shown in FIG. 9(h), the prediction circuit 20 includes the integration circuit 1
The time integral value sent from 5 is transmitted to each antenna 11.12.
The RSS I signals from each antenna 11, 12 within each time slot A are compared and the prediction results are sent to the switching control circuit 18. Switching control circuit 1
8 is time slot A based on the prediction result received.
The antenna 11 (12) with a good reception condition is selected among the antennas 11 (12), and the antenna switch circuit 13 is controlled to connect that antenna 11 (12) to the TDM receiver 14.

[Effects of the Invention] As described above, according to the invention described in claim (1), the reception input electric field level at each antenna immediately before the assigned time slot is time-integrated, and the comparison result of the time-integrated values is calculated. Since the configuration selects the antenna with the best reception condition based on There is an effect that the device can obtain.

Further, according to the invention described in claim (2), the assigned time slot is The structure is configured to predict changes in the received input electric field level at each antenna within a time slot, and select the antenna with the best reception condition based on the prediction results, so it is possible to use time-division radio using linear modulation waves. There is an effect that an effective antenna selection diversity receiving device can be obtained also in a communication system.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an antenna selection diversity receiving device according to an embodiment of the invention as set forth in claim (1);
Figure 2 shows the amplitude of the carrier wave in π/4 shift QPSK.
An explanatory diagram showing the transition on the phase plane, Fig. 3 is an explanatory diagram showing only the envelope level change, and Fig. 4 is an explanatory diagram showing an example of the reception time slot and the input level of each antenna on the time axis. , FIG. 5 is a time chart for explaining the operation of the embodiment shown in FIG. 1, FIG. 6 is a block diagram showing another embodiment of the invention according to claim (1), and FIG. A time chart for explaining the operation, FIG.
2) is a block diagram showing an embodiment of the invention described in 2), FIG. 9 is a time chart for explaining its operation, FIG. 10 is a block diagram showing a control circuit of a conventional antenna selection diversity receiving device, and FIG. The figure is an explanatory diagram showing fluctuations in the received input electric field level at one antenna of a mobile station traveling in an electromagnetic field distribution where fading occurs. Figure 12 is an operation of the control circuit of a conventional antenna selection diversity receiver. FIG. 13 is an explanatory diagram showing the transition of the carrier wave on the vector plane in MSK. 11.12 is an antenna, 13 is an antenna switch circuit,
14 is a radio receiver (TDM receiver), 15 is an integration circuit,
17 is a comparison circuit, 18 is a switching control circuit, and 20 is a prediction circuit. In addition, in the figures, the same reference numerals indicate the same or equivalent parts. Figure 1

Claims (2)

[Claims] (1) Used in a time-division multiplexing wireless communication system using linear modulated waves, the antenna with the best reception condition is selected from among multiple antennas, an antenna switch circuit is controlled, and the selected antenna is transmitted wirelessly. In an antenna selection diversity receiving device connected to a receiver, the reception input electric field level at each of the antennas detected immediately before the time slot assigned to the radio receiver is integrated over a certain period of time, and each time integral value is obtained. an integrating circuit that outputs a signal, a comparing circuit that compares each time integral value from the integrating circuit, and selecting an antenna with the best reception condition based on the comparison result of the comparing circuit, and controlling the antenna switch circuit. An antenna selection diversity receiving device comprising a switching control circuit. (2) Used in a time-division multiplexing wireless communication system using linear modulated waves, which selects the antenna with the best reception condition among multiple antennas, controls an antenna switch circuit, and switches the selected antenna wirelessly. In an antenna selection diversity receiving device connected to a receiver, before a time slot assigned to the wireless receiver, the received input electric field level at each of the antennas detected alternately multiple times is integrated for a certain period of time, an integrating circuit that outputs the time integral value; a prediction circuit that predicts a change in received input electric field level at each antenna within the assigned time slot based on each time integral value from the integrating circuit; An antenna selection diversity receiving device comprising: a switching control circuit that selects an antenna with the best reception condition based on a prediction result of a prediction circuit and controls the antenna switch circuit.